Thermosettable resins generally have limited shelf lives, i.e., upon storage at ambient temperatures the resins undergo premature gelation which, of course, is undesirable. Generally, the tendency of a resin to gel increases as the storage temperature increases and is also dependent on the choice of reactants and on the kind and amount of monomer which is generally mixed with the resin.
Thermosettable vinyl ester resins, unsaturated polyesters or mixtures thereof have similar shelf life or storage stability problems. In the past, attempts with known stabilizing materials to prevent gelation have also resulted in an undesirable increase in the catalyzed gel times of the resins and adversely affected the curability of the resin. Typical of inhibitors taught by the art are certain hydroxyamines as proposed in U.S. Pat. No. 3,408,422 and phenothiazine taught in U.S. Pat. No. 3,683,045.